Textdata

Documentation tweaks.

Updated for new pypi.org URLs.

Plus other minor tweaks, like tightening tox targets in favor of
Travis CI.

*Major* release.

Added ``table()`` and ``records()`` functions for ingesting
tabular and record-oriented data respectively.\

Regularized handling of object evaluation, comment stripping, and
other attributes.

Added pyproject.toml for PEP 518 compliance.

Updated testing matrix to accomodate new PyPy3 version on Travis
CI.

Update compatibility strategy to make Python 3 centric. Python 2
is now the outlier. More future-proof.

Doc tweaks.

Returned test coverage to 100% of lines (introducing `attrs()`
took it briefly down to 99% testing).